function a(x) = 2 * x

open class X {
  function a(x) = 3 * x
  function compute() = a(c)
  c = 3
}

class Y extends X {
  function a(x) = 4 * x
  c = 5
}

res1 = new X {}.compute()
res2 = new X { c = 4 }.compute()
res3 = new Y {}.compute()
res4 = new Y { c = 6 }.compute()
